Magnetic plug



Dec. 17, 1940. 2 4T. E. BROOKS MAGNETIC. PLUG Original Filed June 1, 1937 Patented Dec. 17, 1940 UNITED STATES PATENT OFFICE MAGNETIC PLUG ThomasE.

Clarinda, Iowa, 'assignor to Brooks, Lille Corporation, Ciarinda, Iowa, a corporation 'oflowar Original application June Divided and this 1938,8erialNo. 216,02

1. -1937, Serial No. application June 27,

3 Claims. (01. abs-21s) accidental dislodgement therefrom to thereby provide a magnetic plug adapted for insertion in a lubricant or other opening of a gear housing or the like.

My present application is a division of my '00- pending application Serial No. 1 ,82 filed June 1, 1937.

A further obietc is to provide various arrangements of fastening means which extend through the magnetic core and serve to effectively secure the magnetic corein the shell against accidental displacement therefrom.

Still a further object is to secure a magnetic core in a shell or body so that it will operate efliciently to attract steel or other stray particles within the housing, such housing being ordinarily filled with oil or grease to lubricate the gearing or other mechanism therein.

A further object is to provide fastening means for a magnet relative to a plug or body which does not necessitate drilling a hole or forming other openings in the magnetic cores, which are of extremely hard material and dimcult to machine without aii'ecting their magnetic properties.

With these and other objects in view, my in vention' consists in the construction, arrange-' ment and combination of the various parts of my magnetic plug, whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in my claims, and illustrated in the accompanying drawing, in which:

Figure 1 is a sectional view through the lubricant opening boss of a transmission or other type of gear housing, showing one of my plugs installed relative thereto.

Figure 2 is a plan view of the plug shown in Figure 1.

Figure 3 is a sectional view thereof on the line 3-3 of Figure 2 and showing a. spring clip which has its ends welded in position for retaining the magnet in the shell; and 1 Figure 4 is a sectional view similar to Figure 3 showing a modification in which the spring clip is held in position by the edge of the recess in the plug being sw dged over the upper ends of the clip.

On the accompanying drawing I have used the reference character H to indicate a housing such as one for transmission or diilerential gears or the like. The housing H is provided with a boss III which may be utilized for receiving a drain the recess l3 has plug or a plug which can be removed for introducing lubricant into the housing H'depending of course on the installation. Also, various housings for diflerent types of machinery may be provided with the boss I0 specifically to receive magnetic plugs of the type disclosed forthe purpose of attracting small magnetic particles in the housing and prevent them from entering and damaging gear teeth or other mechanism.

My plug comprises a shell S, a magnet M and 10 means for retaining the magnet in the shell. The shell S has an integral nut portion Ii for removing and positioning the shell relative to the boss I0. The shell has a threaded portion l2 for engagement with the threads of the boss Hi. 15 Within the shell 8 I provide a recess II which is of such size relative to the magnet M that the magnet may fit snugly therein as best illustrated in Figure 2., The shell S may be made of metal of any kind. For instance, brass is suitable although cast iron or the like can be used.

' It is desirable when the metal is ferrous however to provide a spacing or insulating means to get maximum efllciency from the magnet M as too much short-circuiting of the magnetism thereof will lessen the eiliciency to some extent. Such a means is shown in my co-pending application Serial No. 216,083 filed June 27, 1938. However, for all practical purposes such insulation is not necessary.

Preferably the poles of. the magnet M extend slightly beyond the upper end of the shell S so that the strongest magnetic field is thus in position to readily attract particles P from the oil 30 IS in the housing H as shown in Figure 1.

I have shown' a plurality of different methods by which the magnet M may be retained in the shell S. In Figures 1, 2 and 3 the retainer consists of a spring clip 22 welded as indicated at 25 to the shell S and thus retained in position.

The welding 25 is located adjacent the upper edge of the recess l3 where the welding operation can be readily performed and the welding connects the upper end of the clip 22 to the shell S. The clip 22 is V-shapedand its apex engages with the cross member of the magnet M for holding the cross member down against the bottom of the recess l3.

In Figure 4 the edge of the shell S adjacent been swedged at two points indicated at 26 to retain the spring clip 22 and thereby the magnet M in position. This arangement calls for a very simple swedging operation which can be readily performed after the magnet and the clip have been inserted in the recess l3.

From the foregoing description it is obvious that my retainer clip effectively and inexpensively secures a magnetic core within a shell or body to provide a magnetic plug unit for gear housings or the like. 1

Some changes may be made in the arrangement and construction of the various parts of my magnetic plug without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims, any modified forms of structure or use of mechanical equivalents, which may be reasonably included within their scope.

I claim as my invention:

1. A magnetic plug for power transmission housings and the like havinga lubricant opening comprising a magnet of horseshoe type, a body for supporting said magnet, said body being formed to fit in and close said lubricant opening and having in its inner end a recess to receive said magnet with the cross piece thereof seated in said recess, means interlocking with said magnet for retaining it in said body, said means comprising a spring clip extending through said magnet between the poles thereof, the center of said clip engaging the crosspiece of said magnet and projections from said body engaging the ends of said spring clip to retain it and thereby said magnet in position relative to said body.

2. A magnetic plug for power transmission housings and the like having a lubricant opening comprising a horseshoe magnet, a body for supporting said magnet, said body being formed to fit in and close said lubricant opening and having in its inner end a recess to receive the cross piece of said magnet, means interlocking with said magnet for retaining it in said body, said means comprising a retainer for said magnet, means extending from the shell and overhanging the retainer to afiflx it in position, said retainer being interposed in thrust relation between said overhanging means and said cross piece of said magnet.

the center of said clip engaging the crosspiece of said magnet, and means rigid with relation to said body and engaging the terminal ends 01 said spring clip to retain said magnet in position relvative to said body by thrust of the arms or the U-shaped spring clip between said crosspiece and said last means.

THOMAS E. BROOKS, 

